Attentional integration between anatomically distinct stimulus representations in early visual cortex

Abstract

Vision often requires attending to, and integrating information from, distant parts of the visual field. However, the neural basis for such long-range integration is not clearly understood. Here, we demonstrate a specific neural signature of attentional integration between stimuli in different parts of the visual field. Using functional MRI, we found that a task requiring the integration of information between two attended but spatially separated stimuli actively modulated the degree of functional integration (in terms of effective connectivity) between their retinotopic representations in visual cortical areas V1, V2, and V4. Spatial attention enhanced long-distance coupling between distinct neuronal populations that represented the attended visual stimuli, even at the earliest stages of cortical processing. In contrast, unattended stimulus representations were decoupled both from attended representations and particularly strongly from each other. Furthermore, enhanced functional integration between cortical representations was associated with enhanced behavioral performance. Attention may thus serve to ''bind'' together cortical loci at multiple levels of the visual hierarchy that are commonly involved in processing attended stimuli, promoting integration between otherwise functionally isolated cortical loci.attention ͉ connectivity ͉ dynamic causal modeling ͉ functional MRI ͉ vision V ision often requires integration of information from distant locations within the visual field, but how this integration is achieved is currently not well understood. Receptive field properties of visually responsive cortical neurons suggest that, in early visual cortex, information is analyzed largely (although not entirely) locally, with further processing stages combining information from successively larger portions of the visual field (1-3). In such an anatomically convergent pathway, integration of information from distant positions within the visual field might occur entirely in higher visual areas, which have large receptive fields and corresponding possibilities for interactions between distant regions (1-3). However, response properties of cells in early visual areas are also modulated by remote stimuli presented far beyond their classical receptive fields (4-7). Thus, an alternate possibility is that a neural signature reflecting integration of distant information might already be identifiable in very early visual cortex. Possible anatomical substrates for such interactions include long-range horizontal projections within visual areas (8-10), the dense and reciprocal connections between visual areas (7,(11)(12)(13)(14)(15), and subcortical pathways via pulvinar and superior colliculus (16).Here, we used functional MRI (fMRI) in humans to test whether task-dependent interactions between stimulus representations in distant parts of the visual field could be seen in early retinotopic cortex. We placed stimuli in four well separated locations of the visual field and required participants to attend to and integrate informa...

Predicting errors from reconfiguration patterns in human brain networks

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“…It has been shown that attention can modulate interarea correlations between distant cortical regions, independent from changes in regional blood flow (17)(18)(19). However, these studies were usually limited to a small selection of cortical regions (2,7,15,(18)(19)(20).…”

Encoding of Temporal Probabilities in the Human Brain

“…In humans, shifts in the baseline activity of primary visual cortex in the absence of any visual stimulation have been observed (Kastner et al, 1999;Haynes et al, 2005;Silver et al, 2007). This activity is sustained during the time delay preceding stimulus onset, is associated with the deployment of covert spatial attention, and regulated by parietal structures (Chawla et al, 1999;Haynes et al, 2005).…”

“…This activity is sustained during the time delay preceding stimulus onset, is associated with the deployment of covert spatial attention, and regulated by parietal structures (Chawla et al, 1999;Haynes et al, 2005). In the present study we did not explicitly manipulate spatial attention (i.e., spatial expectancy) but instead required participants to focus on temporal expectation.…”

Ventral visual cortex in humans: Cytoarchitectonic mapping of two extrastriate areas

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